Energy requirements for the maintenance and growth of Dorper-Jinzhong crossbred ram lambs

The sheep industry in China has been rapidly developing in recent years; however, the animals’ nutritional requirements under certain conditions have not been thoroughly defined. The objective of this study was to investigate the energy requirements of both the maintenance and growth of Dorper-Jinzhong crossbred ram lambs. Thirty 1/2 Dorper × 1/2 Jinzhong crossed F1 ram lambs (35 ± 0.5 kg of body weight, BW) were randomly selected and divided into five groups in a randomised design for a comparative slaughter trial. The lambs were offered one type of feed at 100%, 65% and 40% of the ad libitum intake. Another 15 lambs were used for the digestibility trial to estimate the metabolisable energy (ME) values of the diet at various feed intake levels. The net energy for maintenance (NEm) and the ME requirement for maintenance (MEm) were 286.68 kJ/kg0.75 of SBW and 437.80 kJ/kg0.75 of SBW, respectively; the energy efficiency for maintenance (km) was 0.655. The net energy for growth (NEg) values for varying average daily gain (100–350 g) in ram lambs grown from 35 to 50 kg increased from 1.31 to 5.93 MJ/d with an energy efficiency for growth (kg) of 0.457. Our results suggest that the energy requirements of Dorper-Jinzhong crossbred ram lambs are lower than the requirements recommended by the National Research Council (NRC) and Agricultural and Food Research Council (AFRC)